Gas boiler cost
A natural gas boiler costs $4,000 to $9,000 installed, and $1,400 to $5,600 for the unit alone. A high-efficiency condensing gas boiler costs $4,000 to $10,000 and can cut heating bills by 10% to 20% compared with an older standard boiler.
Quick answer
$4,000 – $9,000installed
Gas boiler replacements usually cost $4,000 to $9,000. Simple like-for-like swaps can start near $2,200; premium high-efficiency or combi boilers reach about $10,600.
Cost by type
| Type | Installed |
|---|---|
| Conventional gas boiler (80% – 89% AFUE) | $2,200 – $7,000 |
| Condensing gas boiler (90% – 95%+ AFUE) | $4,000 – $10,000 |
| Gas combi boiler | $6,000 – $10,000 |
Sizing a gas boiler
| Home size (sq ft) | Output needed (BTU) |
|---|---|
| 1,200 – 1,600 | 30,000 – 80,000 |
| 1,600 – 2,000 | 40,000 – 100,000 |
| 2,000 – 2,400 | 50,000 – 120,000 |
| 2,400 – 2,800 | 60,000 – 140,000 |
| 2,800 – 3,200 | 70,000 – 160,000 |
| 3,200 – 3,600 | 80,000 – 180,000 |
A heat-loss calculation should set the size. Older boilers are often oversized; right-sizing a new boiler saves fuel and reduces short cycling.
What's included and extras
- Removal of the old boiler: $200 to $500
- Venting changes or a chimney liner for the new unit
- Condensate drain for condensing models: $200 to $600
- Permits: $50 to $250
- Expansion tank, circulator pump and valves if worn
Repair or replace?
Replace a gas boiler that is over 15 to 20 years old with a leaking heat exchanger, frequent pressure problems or rising repair bills. See Boiler replacement cost for all fuels.
How to get a fair quote
- Get at least three written quotes that list the brand, model number, size (tons or BTU) and efficiency rating.
- Ask whether the price includes permits, removal of the old unit, refrigerant, a new thermostat and any duct or electrical work.
- Ask for a load calculation (Manual J) instead of matching the old unit's size by default.
- Compare labor warranties (1 to 10 years) as well as the manufacturer's parts warranty, and register the equipment.
- Schedule non-urgent work in spring or fall, when contractors are less busy and more willing to discount.
Frequently asked questions
How much is a new gas boiler installed?
About $4,000 to $9,000, depending on size, efficiency and venting.
Is a combi boiler worth it?
In smaller homes with modest hot water demand, yes; it replaces the water heater and saves space. Large households may prefer a boiler with an indirect water tank.
How efficient are new gas boilers?
Standard boilers are about 80% to 89% AFUE; condensing boilers reach 90% to 95% or more.
Sources
Prices are national averages and typical ranges from published cost data. Your price depends on your home, region, equipment and contractor, so get several written quotes. Heat & Air Costs is not an HVAC contractor; read our disclaimer.